The Morphology of Asteroidal Dust Around White Dwarf Stars: Optical and Near-infrared Pulsations in G29-38
T. von Hippel, J. Farihi, J. L. Provencal, S. J. Kleinman, J. E. Pringle, A. Swan, G. Fontaine, J. J. Hermes, J. Sargent, Z. Savery, W. Cooper, V. Kim, V. Kozyr… 展开作者
T. von Hippel, J. Farihi, J. L. Provencal, S. J. Kleinman, J. E. Pringle, A. Swan, G. Fontaine, J. J. Hermes, J. Sargent, Z. Savery, W. Cooper, V. Kim, V. Kozyreva, M. Krugov, A. Kusakin, A. Moss, W. Ogloza, E. Pakstiene, A. Serebryanskiy, E. Sonbas, B. Walter, M. Zejmo, S. Zola
More than 36 years have passed since the discovery of the infrared excess from circumstellar dust orbiting the white dwarf G29-38, which at 17.5 pc it is the nearest and brightest of its class. The precise morphology of the orbiting dust remains only marginally constrained by existing data, subject to model-dependent inferences, and thus fundamental questions of its dynamical origin and evolution persist. This study presents a means to constrain the geometric distribution of the emitting dust using stellar pulsations measured at optical wavelengths as a variable illumination source of the dust, which re-radiates primarily in the infrared. By combining optical photometry from the Whole Earth Telescope with 0.7-2.5 micron spectroscopy obtained with SpeX at NASA's Infrared Telescope Facility, we detect luminosity variations at all observed wavelengths, with variations at most wavelengths corresponding to the behavior of the pulsating stellar photosphere, but towards the longest wavelengths the light curves probe the corresponding time-variability of the circumstellar dust. In addition to developing methodology, we find pulsation amplitudes decrease with increasing wavelength for principal pulsation modes, yet increase beyond approximately 2 microns for nonlinear combination frequencies. We interpret these results as combination modes deriving from principal modes of identical l values and discuss the implications for the morphology of the warm dust. We also draw attention to some discrepancies between our findings and theoretical expectations for the results of the non-linearity imposed by the surface convection zone on mode--mode interactions and on the behavior of the first harmonic of the highest-amplitude pulsation mode.
KIC 5623923: A Faint Eclipsing Binary Consisting of $δ$ Scuti pulsations
Xi'an Jiaotong University（西安交通大学）；Yunnan Observatories, Chinese Academy of Sciences（中国科学院云南天文台）；Chinese Academy of Sciences（中国科学院）；Center for Astronomical Mega-Science, Chinese Academy of Sciences（中国科学院国家天文台）；Xinjiang Astronomical Observatory, Chinese Academy of Sciences（中国科学院新疆天文台）；University of Chinese Academy of Sciences（中国科学院大学）
Binarity at LOw Metallicity (BLOeM): massive star variability revealed using a novel software tool for point-spread function fitting of TESS images
Newcastle University（纽卡斯尔大学）；KU Leuven（荷语鲁汶大学）；Tel Aviv University（特拉维夫大学）；University of Amsterdam（阿姆斯特丹大学）；Anton Pannekoek Institute for Astronomy, University of Amsterdam（阿姆斯特丹大学安东·潘内科克天文学研究所）；Universität Bonn（波恩大学）
Wildly Oscillating Stars -- Unexplained dense ridge-like frequency agglomerations in A and F type pulsators
DTU Space, Technical University of Denmark（丹麦技术大学空间中心）；Centre for Astrophysics, University of Southern Queensland（南昆士兰大学天体物理中心）；Centre for Space Research, North-West University（西北大学太空研究中心）；Jeremiah Horrocks Institute, University of Lancashire（兰开夏大学杰里米·霍罗克斯研究所）；Sydney Institute for Astronomy (SIfA), School of Physics, University of Sydney（悉尼大学物理学院悉尼天文研究所）；Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences（波兰科学院尼古拉·哥白尼天文学中心）；TAPIR, Mailcode 350-17, California Institute of Technology（加州理工学院TAPIR）；LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université de Paris（巴黎天文台LESIA实验室（隶属巴黎文理研究大学、法国国家科学研究中心、索邦大学、巴黎大学））；Instutute for Physics and Astronomy, Aarhus University（奥胡斯大学物理与天文学研究所）；STAR Institute, University of Liège（列日大学STAR研究所）
Highly bipolar planetary nebula Hen 2-57 and its possible symbiotic core
Instituto de Astrofísica de Canarias（加那利群岛天体物理研究所）；Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences（波兰科学院尼古拉·哥白尼天文学中心）；Astronomical Observatory, University of Warsaw（华沙大学天文台）
本文通过多波段观测分析高度双极天体 Hen 2-57，发现其具有沙漏形态、中红外过剩及中心核共生星特征，提出其由尘埃包裹的D型共生中央引擎塑造双极星云，是M 2-9的类似体。
